Computed tomography (CT) imaging systems are in wide use today. The CT systems include a gantry that rotates in order to create a 360° image. The gantry icludes an x-ray tube as well as a cooling system to control the temperature of the x-ray tube. The cooling system typically employs a liquid-to-air heat exchanger to remove heat from the x-ray tube during operation. The cooling system also typically includes one or more fans that are used to draw or force air through the heat exchanger and exhaust heated air from the gantry.
The size and surface area of the heat exchanger required in a particular application is partly a function of the power to be dissipated, and the temperature of the ambient air sent through the heat exchanger. On high power CT systems, the ambient air temperature in combination with the higher power requirements often makes the packaging difficult for large heat exchangers.
Also, the rotating gantry is normally encased in a tight fitting cover system, and the cooling air drawn into the heat exchanger is normally supplied by air that is already present in the gantry during operation. The temperature of the cooling air increases as it absorbs heat from the liquid flow to the heat exchanger. The heated air is then expelled from the heat exchanger. Although the heated air is directed to vents in the gantry structure, not all of the air typically exits from the gantry due to the tight spacing between the rotating heat exchanger and the stationary gantry cover. This often allows for above-ambient temperature air to recirculate and be re-ingested into the heat exchanger. This can result in the x-ray tube oil stabilizing at an elevated temperature and possibly reducing the thermal performance of the system.
It would, therefore, be desirable to reduce the amount of heated air that is re-ingested into the heat exchanger and thus improve the thermal performance of the system.